LTE-A, the standard of next-generation mobile communication systems, supports CoMP (coordinated multi-point) and MU-MIMO (multi-user MIMO) to improve data throughput. Here, CoMP refers to a scheme by which two or more base stations (BSs) or cells cooperate with each other to communicate with UEs in order to improve communication performance of UEs and BSs (cells or sectors) located in a gap. CoMP may be classified into CoMP-JP processing (CoMP-JP) in the form of cooperative MIMO through data sharing and CoMP-coordinated scheduling/beamforming (CoMP-CS). According to CoMP-JP, a UE can instantaneously receive data from BSs performing CoMP at the same time and combine signals received from the BSs to improve reception performance. According to CoMP-CS, the UE can instantaneously receive data from one BS through beamforming. MU-MIMO is a scheme through which a BS allocates antenna resources to UEs. According to MU-MIMO, the BS selects a UE capable of achieving high data throughput per antenna and schedules the UE. MU-MIMO improve system throughput.
In addition, next-generation LTE-A is designed to accomplish transmission of a large amount of data. LTE-A employs carrier aggregation (CA) to aggregate a plurality of component carriers (CCs) and to perform transmission through the CCs, thereby improving transmission bandwidth of a UE and increasing frequency use efficiency. LTE-A can extend a bandwidth up to 100 MHz by aggregating a plurality of carriers (i.e. multi-carrier) used in LTE Rel-8/9. In other words, a carrier defined as up to 20 MHz in LTE Rel-8/9 is redefined as a component carrier (or element carrier) and up to 5 component carriers (CCs) can be used by one UE through CA.
A new carrier type is introduced with the introduction of CA. Data instead of control information may be loaded at the start of a specific subframe of a carrier of the new carrier type.
However, a control channel was disposed at the start of a conventional subframe and a UE-specific reference signal mapping pattern was proposed only for this case and a UE-specific mapping pattern for a case in which data instead of the control channel is loaded at the start of the subframe has not been suggested.